Dr. A. Giinther on new Freshwater Fishes. 475 0. pallida^ Marrat, will not agree with any figure or de-scription of 0. scripta^ Lam. There is a very considerable difference between the 0. scripta, Lam., as figured by Reeve, and the 0. scripta^ Lam., as figured by Duclos ; and a much greater difi'erence exists between the shells in my cabinet and the forms figured. 0. similis^ Marrat, is so decidedly distinct as to require no comment. 2 Peveril Terrace, Edge Laue, Liverpool. May 16, 1808. LVI. — Diagnoses of some new Freshwater Fishes from. Suri-nam and Brazil, in the Collection of the British Museum. By Dr. Albeet Gunther. The Trustees of the British Museum obtained, in the course of last year, several collecti.>ns of South-American Fishes, of which we may mention that made by Mr. Edward Bartlett on the Huallaga and at Xeberos (Upper Amazons), others sent by Hr. Kappler from the Maroni River (Surinam), and, finally, numerous examples from Surinam, formerly in the museum of the late Dr. van Lidth de Jeude. For the present I give the diagnoses of those species which I have found to be undescribed ; and more detailed descriptions with illustrations will be published in the ' Proceedings of the Zoo-logical Society,' before which the paper was read on March 26. Doras helicophilus. Lateral shields well developed, entirely uncovered by the skin ; the depth of the third is one-half of the length of the head, those on the tail only half as deep as the tail ; their whole surface is covered with minute spines. Humeral process without spines, with a very slight ridge extending to the hinder third of the pectoral spine. The posterior lobes of the nuchal carapace are rounded, reaching to the base of the se-cond soft ray of the dorsal fin. Dorsal spine serrated in front and behind, the anterior denticulations being directed upwards. Caudal peduncle shielded above and below. Uniform blackish ; dorsal fin white, the middle black. Surinam. Oxydoras acipenserinus. This fish is distinguished from all its congeners by the pe-culiar shape of the head and snout, which is elongate triangular, pointed, and much depressed in its anterior portion. L. lat.42. Xeberos. 33*
BioStor
